Most of the hundreds of signs held aloft by immigration demonstrators Saturday afternoon were professionally printed — slick, camera-ready fliers handed out by organizers — but one stood out. Written in brightly colored markers and replete with glitter glue, it said: “LEGALIZE MY MOM!”

Daniela Zarate, 20, was the sign’s owner. She helped lead a contingent of Williams College students to a rally for immigration policy changes orchestrated by the Massachusetts Immigrant and Refugee Advocacy Coalition.

The event, which saw about 750 demonstrators march from Copley Square to Boston Common, was one of more than 100 similar demonstrations nationwide on Saturday.

The rallies are part of a push by advocates to pressure federal lawmakers into delivering comprehensive changes that would give millions of illegal immigrants the right to drive, attend state universities and colleges for the in-state rate, and to eventually become US citizens.

“My mom was 18 and pregnant when she crossed the border,” Zarate said, detailing how she, her mother, and her two siblings then lived in fear in San Diego with her abusive father, a US citizen who had brought them over. “We knew my mother was illegal, and we never wanted to call the police to tell them about our situation because we thought they were going to deport her. And we had to live under that regime until I was 18.”

Zarate said her mother, who works as a housekeeper, is exactly the sort of person who would benefit from — and deserves — a pathway to becoming a legal resident.

“My mother has been here for 24 years, and the worst she’s ever done is gotten a speeding ticket for trying to get me to school on time,” Zarate said. “She works from 7 in the morning to 7 at night for almost nothing. . . . We don’t come here to mooch off the country and take jobs away from people. We’re the people doing the jobs that no one really wants.”

The long-planned series of rallies, set to culminate in a march on the Mall in Washington Tuesday, brought together a broad coalition of faith, labor, and advocacy groups. Those organizations, groups bused in from Worcester, Brockton, and other communities, mixed freely at Saturday’s rally in Boston.

JOHN TLUMACKI/GLOBE STAFF

Demonstrators marched down Boylston Street in Boston.

Police temporarily closed Boylston Street in the Back Bay while the group marched down the street, chanting, “Yes, we can!” in Spanish as tourists and shoppers enjoying the warm fall day watched.

Boston City Councilor Ayanna Pressley attended the rally, saying that while local leaders cannot set immigration policy, they must help organize their constituents to pressure federal legislators.

“I can’t believe that in 2013 we are still fighting this fight,” Pressley said in an interview. “We’re really just one country and one community. Whenever the bonds of community are broken . . . we have to remedy that. It’s everyone’s problem.”

Advocates at the rally also decried federal policies that divide families based on seemingly insignificant variations in circumstances.

When the Obama administration implemented the Deferred Action for Childhood Arrivals memorandum in 2012, then-29-year-old Samantha Almeida of Everett thought she finally had a chance to get a driver’s license and qualify for in-state tuition at the Massachusetts state universities and colleges where she longed to study.

But after spending weeks gathering the required documentation and filling out forms, Almeida learned she was ineligible because she had arrived here with her mother from Brazil just after her 16th birthday in 1999.

To qualify, immigrant children must have arrived before they turn 16.

“I was angry, I was yelling, I was crying,” Almeida said. “I had everything set up. I still have my folder with all my papers and all the proof and everything.”

Almeida’s 25-year-old brother qualified under the order, however; he now has a driver’s license and enrolled in college last month.

Almeida continues to work in catering and says she lives in fear of being pulled over by police and deported.

The siblings’ two outcomes illustrate how arbitrary immigration policy can seem at the individual level, Almeida said.

“I was happy for my brother, because the dreams that I have, he has, and he was fulfilling his dreams,” she said. “But I felt bad for my mom. She couldn’t be happy for my brother because she was feeling bad for me.”

Her brother feels guilty, she said.

“But I tell him, ‘John, it’s not your fault. You keep going. When I get my papers, then it will be my turn to go after my dreams.’ ”

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